Inside our bodies we host a world one could base a fantasy novel on. Tiny characters in a landscape of blood and tissue take on tactical invaders in a fight between the good and the bad, in a constant battle for homeostasis. When baddies mutate and gather for a fresh attack, the good guys are sometimes caught off guard and unable to strategise. By supplying tools, for example, a vaccine, they can prepare a small but mighty army. Our bodies are remarkably clever. Unfortunately, the brain’s ability to perceive what’s happening is not straightforward. We are subject to floods of information and susceptible to persuasion.

Our brain’s ability to extricate good information from bad information is hin